Security guard forces have long been employed to patrol and protect property against unauthorized intrusion and vandalism. Such forces are common in large industrial complexes housing valuable equipment, inventory, or sensitive information. These complexes include, for example, store rooms, computer rooms, warehouses, manufacturing facilities, office buildings, military bases, department stores and the like. Prior to the introduction of portable two-way radios, such complexes would usually be patrolled by a team of guards with each guard periodically patrolling a designated area of the complex and returning to a central station to report. Obviously, this left most areas of the complex unattended for long periods of time between patrols.
With the introduction of portable two-way radios, each guard of a team could be stationed permanently in his designated area and could report in periodically to a central station via radio. He could also receive instructions via radio from the central dispatcher so that he could be advised quickly and efficiently of a change in his assignment or of an unusual or threatening situation. While such a system is an improvement over roving patrols, it is still subject to numerous inherent problems. The guards, for example, being human, are subject to inattention and can sometimes be evaded by a clever intruder. This is particularly true in situations where little or no activity over long periods of time can lead to extreme boredom and fatigue among the guards. Probably the most serious problem with posted human sentries is the extremely high cost in salaries and benefits of maintaining the necessarily large security force. Further, frequent turnover among security guards can lead to high training costs and reduced overall efficiency.
In recent years, electronic security systems have found widespread use as an adjunct to traditional radio dispatched security guard forces. Such systems can include passive infrared or heat sensors mounted in designated areas of a guarded complex and positioned to detect the presence of a person within the area. Upon such detection, the sensor, which is usually hard wired to a central control, signals the central control, which can emit a visual or audible signal indicating that an intruder has been detected.
Such security systems have allowed reduction in the number of persons required to guard a complex. Further, they are not subject to boredom, fatigue and evasion as human sentries can be. However, these motion detecting security systems are relatively simple, are not generally portable or easily adaptable to changing requirements, and convey no useful information in addition to a simple signal that a detection has been made. Accordingly, a guard responding to a detection must enter the monitored area with little or no information about where in the area the intruder was detected or how he may have been moving within the area.
Thus, a continuing and unaddressed need exists for an electronic security sentry system adapted to serve as an adjunct to a security guard force and capable of continuous surveillance of a designated area to detect any unauthorized presence. The system should be completely portable and easily adaptable to changing locations, time schedules, and circumstances. Upon a detection, the system should report to the entire guard force by two-way radio and in spoken words the details of the detection. Reports of other conditions such as time, temperature, tampering, and moisture presence should also be provided. It is to the provision of such a system that the present invention is primarily directed.